NEW YORK, NY - DECEMBER 14: Steve Mnuchin, President-elect Donald Trump's nominee for Treasury Secretary, arrives at Trump Tower, December 14, 2016 in New York City. This is the first major meeting between President-elect Trump and technology industry leadDrew Angerer/gettyimages

Steve Mnuchin, President-elect Donald Trump's pick to lead the Department of the Treasury, faced a tough crowd in his confirmation hearing Thursday.

Oregon Sen. Ron Wyden came out swinging, beginning his remarks with a description of "truly disgusting inequity and abuse" of the U.S. tax code through the use of offshore accounts.

Mnuchin has offshore investments in the Cayman Islands, a tax shelter, which was among many assets that Democrats charge Mnuchin failed to properly list in his early ethics disclosures, according to a CNN Money report.

Wyden continued to dig in during questioning.

At one particularly contentious moment, Ohio Sen. Sherrod Brown accused Mnuchin of being "defensive," and deflecting on questions about whether or not OneWest illegally evicted active duty veterans"

During the line of questioning, Mnuchin appeared to lose his cool, saying "you just want to shoot questions at me."

There's perhaps a reason why Democrats smell blood in water.

Mnuchin is reportedly at the top of the list of potential opportunities for Democrats to block one of Trump's nominees in the confirmation process — and transition insiders told Axios that Trump may not be willing to go to bat for the Treasury pick, either.

Here's why.

Mnuchin reportedly isn't a darling of the transition team

According to the Axios report, Mnuchin's preparations for his hearings didn't go so well, and he came across as "stiff and uneven."

Insiders also expressed concerns, according to writer Mike Allen, about potential demonstrators and how Mnuchin would react.

To address these last-minute concerns, additional consultants were flown in to help him get ready; Axios also reports that Trump's transition officials were annoyed when Mnuchin leaked his appointment to the press.

One West, a past Mnuchin project, has been characterized as a "foreclosure machine"

One of the biggest controversies surrounding Mnuchin has to do with a bank he and his partners acquired during the financial crisis, IndyMac, which the group later renamed One West.

Home owners protest Indy Mac bank, in front of the offices of OneWest Bank Center, who previously bought home loans from Indy Mac bank, Tuesday Nov. 24, 2009 in Pasadena, Calif. They are joining a protest by families affected by Indy Mac's refusal to modify loans, causing families to go into foreclosure and subsequently lose their homes. (AP Photo/Damian Dovarganes)Damian Dovarganes/AP

During Mnuchin's tenure with One West, the bank foreclosed on as many as 36,000 homes, while Mnuchin may have made as much as $200 million in the process.

The opposition has carefully unearthed some of the victims of these foreclosures, which reportedly includes a 90-year-old woman who only owed 27 cents.

Mnuchin immediately countered these claims in his opening testimony, characterizing himself as rescuing a troubled bank, saying "my group had nothing to do with the creation of risky loans in the IndyMac loan portfolios," and noting he saved "thousands of jobs," according to an NPR report.

Mnuchin's bank has also been accused of redlining and racial discrimination

Mnuchin may have a point that the characterization of his bank as a foreclosure machine could have a touch of partisan spirit to it — there were lots of troubled banks during the financial crisis that desperately needed buyers. But the disproportionately low number of minority borrowers serviced by his bank is harder to defend.

Across more than 50 California branches, One West gave just two loans to black borrowers in 2014 and 2015 and had far lower rates of enrolling Asian and Hispanic borrowers than peer institutions, according to Bloomberg and Los Angeles Times reports.

If confirmed, Mnuchin would be one of the most important members of Trump's cabinet, and fifth in line to the presidency.